Energy-Efficient Base Station With Synchronization

ABSTRACT

Systems, methods and computer software are disclosed for providing an energy efficient base station with synchronization. In one embodiment, a method is disclosed, comprising: performing traffic analysis to determine off-peak hours duration when traffic is light; updating downlink and uplink schedulers to transmit a minimum required signaling and control information; and wherein updating downlink and uplink scheduler for minimum required signaling and control information further comprises scheduling, in a downlink direction, at least one of transmitting only reference symbols over selected OFDM symbols, PDDCH on to a first three OFDM symbols, PSS and SSS on a central six PRBs and PBCH.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/813,244, filed Mar. 9, 2020, which claims priority under 35 U.S.C. §119(e) to U.S. Provisional Pat. App. No. 62/816,027, filed Mar. 8, 2019,titled “Energy-Efficient Base Station with Synchronization”, each ofwhich is hereby incorporated by reference in its entirety for allpurposes. This application also hereby incorporates by reference, forall purposes, each of the following U.S. Patent Application Publicationsin their entirety: US20170013513A1; US20170026845A1; US20170055186A1;US20170070436A1; US20170077979A1; US20170019375A1; US20170111482A1;US20170048710A1; US20170127409A1; US20170064621A1; US20170202006A1;US20170238278A1; US20170171828A1; US20170181119A1; US20170273134A1;US20170272330A1; US20170208560A1; US20170288813A1; US20170295510A1;US20170303163A1; and US20170257133A1. This application also herebyincorporates by reference U.S. Pat. No. 8,879,416, “Heterogeneous MeshNetwork and Multi-RAT Node Used Therein,” filed May 8, 2013; U.S. Pat.No. 9,113,352, “Heterogeneous Self-Organizing Network for Access andBackhaul,” filed Sep. 12, 2013; U.S. Pat. No. 8,867,418, “Methods ofIncorporating an Ad Hoc Cellular Network Into a Fixed Cellular Network,”filed Feb. 18, 2014; U.S. patent application Ser. No. 14/034,915,“Dynamic Multi-Access Wireless Network Virtualization,” filed Sep. 24,2013; U.S. patent application Ser. No. 14/289,821, “Method of ConnectingSecurity Gateway to Mesh Network,” filed May 29, 2014; U.S. patentapplication Ser. No. 14/500,989, “Adjusting Transmit Power Across aNetwork,” filed Sep. 29, 2014; U.S. patent application Ser. No.14/506,587, “Multicast and Broadcast Services Over a Mesh Network,”filed Oct. 3, 2014; U.S. patent application Ser. No. 14/510,074,“Parameter Optimization and Event Prediction Based on Cell Heuristics,”filed Oct. 8, 2014, U.S. patent application Ser. No. 14/642,544,“Federated X2 Gateway,” filed Mar. 9, 2015, and U.S. patent applicationSer. No. 14/936,267, “Self-Calibrating and Self-Adjusting Network,”filed Nov. 9, 2015; U.S. patent application Ser. No. 15/607,425,“End-to-End Prioritization for Mobile Base Station,” filed May 26, 2017;U.S. patent application Ser. No. 15/803,737, “Traffic Shaping andEnd-to-End Prioritization,” filed Nov. 27, 2017, each in its entiretyfor all purposes, having attorney docket numbers PWS-71700US01, US02,US03, 71710US01, 71721US01, 71729US01, 71730US01, 71731US01, 71756US01,71775US01, 71865US01, and 71866US01, respectively. This document alsohereby incorporates by reference U.S. Pat. Nos. 9,107,092, 8,867,418,and 9,232,547 in their entirety. This document also hereby incorporatesby reference U.S. patent application Ser. No. 14/822,839, U.S. patentapplication Ser. No. 15/828,427, U.S. Pat. App. Pub. Nos.US20170273134A1, US20170127409A1 in their entirety.

BACKGROUND

The downlink physical layer of LTE is based on orthogonalfrequency-division multiple access (OFDMA) and offers followingbenefits: long symbol time and guard interval increases robustness tomultipath and limits intersymbol interference; eliminates the need forintracell interference cancellation; allows flexible utilization offrequency spectrum; increases spectral efficiency due to orthogonalitybetween sub-carriers; allows optimization of data rates for all users ina cell by transmitting on the best (i.e. non-faded) subcarriers for eachuser; data traffic, control channels that carry information on thenetwork and cell, and reference symbols that assist in propagationchannel response can be interspersed. The uplink physical layer of LTEis based on single carrier frequency division multiple access (SC-FDMA).

A UE (user equipment) or other mobile device that attaches to a nearbycell will obtain a primary sync signal and a secondary sync signal fromthe cell, which together enable the UE to calculate a physical cellidentity (PCI). There are 504 different combinations available for thePCI, based on characteristics of the primary and secondary sync signals.A mobile network may include more than 504 cells, but this is typicallyhandled by ensuring that the same PCI is not used for adjacent cells.

SUMMARY

Long Term Evolution (LTE) physical layer uses Orthogonal FrequencyDivision Multiplex (OFDM) for high peak transmission rate (100 MbpsDownlink/50 Mbps Uplink). In addition, LTE network uses multiple antennatechniques such as MIMO (Multiple Input Multiple Output) to increasecapacity or enhance signal robustness. However, this benefits are notwithout drawbacks, such as, increased power consumption at the basestation due to the need of use of power amplifiers.

Therefore, there is a need for energy efficient base station. Methods ofproviding energy-efficient base station are disclosed usingreconfiguring the uplink and downlink scheduler at the eNodeB, in bothtime and frequency domains, to selectively turn on and off the key powerconsuming building blocks to improve the efficiency. The disclosedmethods may improve the efficiency by a factor of 10 to 20.

System, methods and software for providing an energy-efficient basestation with synchronization. In one embodiment a method may bedisclosed, the method including performing traffic analysis to determineoff-peak hours duration when traffic is light; updating downlink anduplink schedulers to transmit a minimum required signaling and controlinformation; and wherein updating downlink and uplink scheduler forminimum required signaling and control information further comprisesscheduling, in a downlink direction, at least one of transmitting onlyreference symbols over selected OFDM symbols, PDDCH on to a first threeOFDM symbols, PSS and SSS on a central six PRBs and PBCH. The method mayfurther include updating downlink and uplink scheduler for minimumrequired signaling and control information by scheduling, in an uplinkdirection, transmitting at least one of only PUCCH and PRACH.

In another embodiment, a computer readable medium may be disclosed forproviding an energy-efficient base station with synchronization. Thecomputer-readable medium contains instructions for providing an energyefficient base station with synchronization which, when executed, causea node to perform steps including performing traffic analysis todetermine off-peak hours duration when traffic is light; updatingdownlink and uplink schedulers to transmit a minimum required signalingand control information; and wherein updating downlink and uplinkscheduler for minimum required signaling and control information furthercomprises scheduling, in a downlink direction, at least one oftransmitting only reference symbols over selected OFDM symbols, PDDCH onto a first three OFDM symbols, PSS and SSS on a central six PRBs andPBCH. The computer readable medium may further include instructions forupdating downlink and uplink scheduler for minimum required signalingand control information by scheduling, in an uplink direction,transmitting at least one of only PUCCH and PRACH.

In another embodiment, a system may be disclosed for providing anenergy-efficient base station with synchronization, the system includinga node configured to perform traffic analysis to determine off-peakhours duration when traffic is light; update downlink and uplinkschedulers to transmit a minimum required signaling and controlinformation; and wherein the downlink and uplink scheduler are updatedfor minimum required signaling and control information, includingscheduling, in a downlink direction, at least one of transmitting onlyreference symbols over selected OFDM symbols, PDDCH on to a first threeOFDM symbols, PSS and SSS on a central six PRBs and PBCH. The system mayupdate downlink and uplink scheduler for minimum required signaling andcontrol information by scheduling, in an uplink direction, transmittingat least one of only PUCCH and PRACH.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing downlink reference symbols within a RB for aone antenna system for normal CP, in accordance with some embodiments.

FIG. 2 is a diagram showing uplink demodulation and sounding channelreference signals in normal CP mode, in accordance with someembodiments.

FIG. 3 is a diagram showing a synchronization signal frame and slotstructure in a time domain, in accordance with some embodiments.

FIG. 4 is a diagram showing a synchronization signal frame and slotstructure in a time domain, in accordance with some embodiments.

FIG. 5 is a diagram showing synchronization signals frame structure infrequency and time domain, in accordance with some embodiments.

FIG. 6 is a diagram showing synchronization signals frame structure infrequency and time domain, in accordance with some embodiments.

FIG. 7 is a diagram showing BCH structure, in accordance with someembodiments.

FIG. 8 is a diagram showing control channel signaling region using threeOFDM symbols, in accordance with some embodiments.

FIG. 9 is a diagram showing a physical uplink control channel structure,in accordance with some embodiments.

FIG. 10 is a diagram showing a physical uplink control channelstructure, in accordance with some embodiments.

FIG. 11 is a diagram showing random access preamble, in accordance withsome embodiments.

FIG. 12 is a diagram showing random access preamble, in accordance withsome embodiments.

FIG. 13 is a flow diagram showing an embodiment for performingenergy-efficient base station with synchronization, in accordance withsome embodiments.

FIG. 14 is a diagram showing an exemplary deployment scenario, inaccordance with some embodiments.

FIG. 15 is a diagram showing ran exemplary eNodeB, in accordance withsome embodiments.

FIG. 16 is a diagram showing an exemplary coordinating server, inaccordance with some embodiments.

DETAILED DESCRIPTION

FIG. 1 is a diagram 100 showing the location of downlink referencesymbols within a RB for a one antenna system for a normal CP. Forcoherent demodulation at the user equipment (UE), reference symbols(RSs) are inserted in the OFDM time-frequency grid to allow for channelestimation. Downlink reference symbols are inserted within the first andthird last OFDM symbol of each slot with a frequency domain spacing ofsix sub carriers. In case of two transmit antennas, reference signalsare inserted from each antenna, where reference signals on the secondantenna are offset in the frequency domain by three subcarriers. Nothingis transmitted on the other antenna at the same time-frequency locationof the reference signals to allow the UE to accurately estimate thechannel coefficients.

FIG. 2 is a diagram 200 showing uplink demodulation and sounding channelreference signals (normal CP mode). There are two types of referencesignal for uplink transmission: Demodulation Reference Signals (DM-RS)and Sounding Reference Signal (SRS). DM-RS is time multiplexed withuplink data and are used to enable coherent signal demodulation at thebase station, e.g. eNodeB. SRS is used to allow channel dependent uplinkscheduling and is shared among users with different transmissionbandwidth.

FIG. 3 and FIG. 4 are diagrams 300 and 400 showing synchronizationsignal frame and slot structure in time domain. There are two types ofreference signal for uplink transmission: Demodulation Reference Signals(DM-RS) and Sounding Reference Signal (SRS). DM-RS is time multiplexedwith uplink data and are used to enable coherent signal demodulation atthe base station, e.g. eNodeB. SRS is used to allow channel dependentuplink scheduling and is shared among users with different transmissionbandwidth

Synchronization sequences represent series of steps performed by a userequipment (UE) to access the LTE system during cell search.Synchronization sequences during cell search helps UE to determine timeand frequency parameters required to demodulate downlink signals; totransmit with correct timing; and to acquire some critical systemparameters. There are three synchronization requirements: symbol timingacquisition, to determine correct symbol start, carrier frequencysynchronization to mitigate the effect of frequency errors resultingfrom Doppler shift and errors from electronics components and samplingclock synchronization

UE uses following two special signals broadcast on each cell by the basestation during cell search procedure for initial access to an LTE systemand for handover to a neighbor cell: Primary Synchronization Sequence(PSS) and Secondary Synchronization Sequence (SSS). Detection of PSS andSSS allows the UE to complete time and frequency synchronization and toacquire useful system parameters, e.g., cell identity, access mode(TDD/FDD), and cyclic prefix length. Synchronization signals aretransmitted twice per radio frame of 10 ms duration. SynchronizationSignals (Reference Symbol, PSS, SSS) in a frame structure for time andfrequency domain.

FIG. 5 and FIG. 6 are diagrams 500 and 600 showing synchronizationsignals frame structure in frequency and time domain. FIG. 5 and FIG. 6shows unused resources are turned off if not required.

FIG. 7 is a diagram 700 showing PBCH Structure. In an LTE system,downlink physical channels, transport channel and control channel, carryinformation blocks received from the medium access control (MAC) andhigher layers. Transport Channels include Physical Broadcast Channel(PBCH), structure shown in FIG. 10, Physical Downlink Shared Channel(PDSCH) and Physical Multicast Channel (PMCH).

The Physical Broadcast Channel (PBCH) broadcasts a below listed limitednumber of parameters essential for initial cell access in 14 bits longMaster Information Block. Downlink system bandwidth, Physical Hybrid ARQIndicator Channel structure and the most significant eight-bits of theSystem Frame Number. PBCH is detectable without prior knowledge ofsystem bandwidth and accessible at cell edge, thereby making the basestation detectable in a cell.

The Physical Downlink Shared Channel (PDSCH) is the main data bearingchannel allocated to users on a dynamic and opportunistic basis.Transmits broadcast information not transmitted on PBCH, e.g., SystemInformation Blocks (SIB) and paging messages.

The Physical Multicast Channel (PMCH) is a physical layer structure tocarry multimedia broadcast and multicast services (MBMS).

FIG. 8 shows two diagrams 800 and 801 for Control Channel SignalingRegion (3 OFDM Symbol Example). The control channel occupies the first1, 2, or 3 OFDM symbols in a subframe extending over the entire systembandwidth. In narrow band systems, i.e. less than 10 RBS, the controlsymbols can include four OFDM symbols. The Control channels for downlinktransmission are: Physical Downlink Control Channel (PDCCH), PhysicalControl Format Indicator Channel (PCFICH), and Physical Hybrid ARQIndicator Channel (PHICH).

Physical Downlink Control Channel (PDCCH) carries resource assignmentinformation for UEs contained in Downlink Control Information (DCI)message. Multiple PDCCHs can be transmitted in the same subframe usingControl Channel Elements (CCE) each of which is a nine set of fourresource elements known as Resource Element Groups (REG). Uses QPSKmodulation

Physical Control Format Indicator Channel (PCFICH) carries ControlFramer Indicator (CFI), which includes the number of OFDM symbols usedfor control channel transmission in each subframe. Typically 1, 2, or 3OFDM symbols. 32-bit long CFI mapped to 16 Res in the first OFDM symbolof each downlink frame using QPSK modulation.

Physical Hybrid ARQ Indicator Channel (PHICH) carries Hybrid ARQACK/NAK, which indicates to the UE whether the base station correctlyreceived uplink user data carried on the physical uplink shared channel(PUSCH). Uses BPSK modulation.

FIG. 9 and FIG. 10 are diagrams 900 and 1000 of the Physical UplinkControl Channel Structure. There are three physical layer channelsdefined for uplink transmission in LTE: Physical Uplink Shared Channel(PUSCH), Physical Uplink Control Channel (PUCCH), shown in FIG. 9 andFIG. 10 and Physical Random Access Channel (PRACH). As shown in FIG. 10,a resource may be turned off if there is no data.

Physical Uplink Shared Channel (PUSCH) carries user data, and anycontrol information necessary to decode information such as formatindicators and MIMO parameters. Scheduling interval is similar to thedownlink. Supports QPSK, 16 QAM, and 64 QAM (optional) modulation.

Physical Uplink Control Channel (PUCCH) carries Control signalingcomprising HARQ ACK/NACK, Channel quality indicators (CQI), MIMOfeedback (Rank Indicator, RI; Precoding Matrix Indicator, PMI),scheduling requests for uplink transmission, supports BPSK or QPSKmodulation and Typical number of PUCCH regions for different systembandwidths shown below in TABLE 1

System Bandwidth (MHz) 1.25 2.5 5 10 15 20 PUCCH Control Regions 1 2 4 812 16 Number of Resource Blocks 2 4 8 16 24 32

Physical Random Access Channel (PRACH) carries random access preamble aUE sends to access the network in non-synchronized mode and used toallow the UE to synchronize timing with the base station. Variouspreamble formats with different preamble and cyclic prefix durationaccommodates different cell sizes. Preamble format 0, which is wellsuited for small to medium cell size cells, shown in FIG. 11 and FIG.12. FIGS. 12 and 13 show a Random Access Preamble 1100 and 1200.

Technical Solution

In an example embodiment, a method to achieve energy efficiency for a 4GLTE eNodeB includes through statistical analysis identify the period ofa day when there are very few users in the system, or identify the LTEusers that can be offloaded to another access mechanism or radio accesstechnology (RAT) system. Use adaptive beamforming techniques to reducethe cell size to handover users to macro base station. Energy efficiencycan be achieved by transmitting only the following on downlinkdirection: reference symbols on selected tones over selected OFDMsymbols, PDCCH on to the first 3 OFDM symbols, PSS and SSS on thecentral 6 PRBs and PBCH. The above listed channels are bare minimum forbase station detection by the UE during cell search procedure. Onlyenable PUCCH and PRACH for the uplink transmission, and turn offeverything else in the uplink direction. For a 20 MHz LTE system with100 PRBs, only 8 PRBs (max) for PUCCH and 6 PRBs for PRACH needed. Inthe frequency domain, overall energy efficiency may be improved byconfiguring PUCCH and PRACH in a sparse manner.

Since very few users are active during the identified off-peak hours ornight time, and only a bare minimum signals are transmitted by the basestation, in yet another embodiment, only one transmit antenna issufficient to transmit the minimum required signaling tones(antenna/MIMO muting). This brings additional benefit of turning offpower amplifiers for disabled transmit antenna during off-peak hours ornight time. This only requires 1/10th or 1/20th of the maximum powerduring the base station idle mode operation.

Antenna/MIMO Muting

MIMO is not energy efficient when there is no data to transmit,particularly during off-peak hours and night time. Turning off MIMO,therefore, during off-peak hours reduces power consumption. Similarly,antennas may also be turned off during off-peak hours and may furtherreduce base station's power consumption. Because additional antennas aremuted, associated power amplifiers are also turned off, and increaseenergy efficiency of the base station significantly.

While the above embodiments for improving energy efficiency may beimplemented at the base station supporting multi radio access technologysuch as 2G, 3G, 4G, 5G, Wi-Fi etc., the coordinating server situated inthe radio access network (RAN), and acting as a gateway between basestations in the RAN and the mobile core network, may also collectnecessary information from the base stations over X2 interface andprovide instructions to the base stations for improving energyefficiency at the base stations. The sample base station and thecoordinating server are shown here.

Flow charts of particular embodiments of the presently disclosed methodsare depicted in FIG. 13. The rectangular elements are herein denoted“processing blocks” and represent computer software instructions orgroups of instructions. Alternatively, the processing blocks representsteps performed by functionally equivalent circuits such as a digitalsignal processor circuit or an application specific integrated circuit(ASIC). The flow diagrams do not depict the syntax of any particularprogramming language or hardware implementation. Rather, the flowdiagrams illustrate the functional information one of ordinary skill inthe art requires to fabricate circuits or to generate computer softwareto perform the processing required in accordance with the presentinvention. It should be noted that many routine program elements, suchas initialization of loops and variables and the use of temporaryvariables are not shown. It will be appreciated by those of ordinaryskill in the art that unless otherwise indicated herein, the particularsequence of steps described is illustrative only and can be variedwithout departing from the spirit of the invention. Thus, unlessotherwise stated the steps described below are unordered meaning that,when possible, the steps can be performed in any convenient or desirableorder.

FIG. 13 shows a flow diagram of a method 1300 for providing anenergy-efficient base station with synchronization. Processing block1301 recites performing traffic analysis to determine off-peak hoursduration when traffic is light. Using self-organizing network (SON)module and analysis of the big data and user reports for various useractivity, billing records, handover requests, etc. identify active userstraffic pattern. Based on analysis, determine the time of a day, the dayof a week, when the number of active users are below a user definedthreshold value (off-peak hours) to trigger actions for energy efficient4G LTE eNodeB.

Processing block 1302 discloses identifying user equipments to handoverto macro base station or neighboring base station. The 4G LTE eNodeB canincrease its energy efficiency during the off-peak hours if it canhandover user equipments latched to the eNodeB to macro base station. Asmore user equipments are served by the macro base station or neighboringcells, the energy efficiency can be increased as less power is needed toserve the users

Processing block 1303 states performing adaptive beam-forming to updatecell size. In order to handover the user equipments latched to theeNodeB to neighboring cells or macro base stations, techniques to reducethe cell size may be employed. Technologies such as beam tilt,multi-beam, adaptive array and active antennas may be used to fit thedesired capacity and coverage requirement during off-peak hours.

Processing block 1304 discloses updating downlink and uplink schedulerfor only minimum required signaling and control information. Furtherenergy efficiency may be achieved by updating uplink and downlinkscheduling of the 4G LTE eNodeB, either at the LTE eNodeB or at acoordinating server, to transmit only bare minimum signaling tones andcontrol channel signaling e.g., in the downlink direction, schedulingmay be updated to transmit only: reference symbols on selected tonesover selected OFDM symbols PDCCH on to the first 3 OFDM symbols, PSS andSSS on the central 6 PRBs, PBCH, and e.g., in the uplink direction,scheduling may be updated to transmit only PUCCH and PRACH.

Processing block 1305 recites turning off additional antennas, poweramplifiers and MIMO. Since the number of users being served by 4G eNodeBare reduced through measures take at blocks 1302 and 13033, further moreenergy efficiency may be achieved by antenna and MIMO muting, andturning off power amplifiers. Only power amplifier for active antennamay be required to be turned on

RF Power Amplifiers of 2G/3G base station system consumes large amountof power. Therefore, decreasing the power used at the power amplifier istop most factor for increasing the energy efficiency for 2G/3G basestation.

The following techniques may be employed to increase energy efficiency:increase the linearity of the power amplifier: linearity of the poweramplifier may be increased using feedforward, pre-distortion, cartesianfeedback, digital pre-distortion, Doherty Power Amplifier, and crestfactor reduction. While LD-MOS power transistor is used currently forbase station amplifier,

Gallium Nitride (GaN) based semiconductor power devices or RF componentsmay be used to improve energy efficiency.

Method to Achieve Energy Efficiency for a 2G/3G Base Station

Remove the feeder cable loss by reducing the distance between theantenna and the base station with RF equipment and amplifier modules. Amulti-sector base station tower configured with radio heads mounted in atriangular configuration, where the base station may be located veryclose to the remote radio heads (RRHs) reduces the feeder cable losscaused in a typical deployment. The short distance and placement of thebase station and RRHs as described above allows the use ofhigh-bandwidth radio technologies, e.g., Wi-Gig, etc.

Further energy efficiency may be achieved through base station siteoptimization by using natural cooling instead of electrical power basedcooling system since base station is mounted on a tower. Using alternateenergy sources, e.g., solar panels, wind power, fuel cell, picohydro,etc., based on the environment of the base station deployment site togenerate or supplement the necessary electrical power requirements.Configuring antennas and power amplifiers in either standby or shutdownmode based on analysis of the traffic pattern during off-peak traffichours improves energy efficiency of the 2G/3G base station system.

A 5G base station with a massive MIMO system offers benefit of improvedtransmission rate, but contrary to 2G/3G/4G base station, the 5G basestation consumes slightly more than 50% of total energy, i.e., energyrequired for transmission power is comparable to computational power atthe base station. Techniques used for energy efficiency for 4G LTEeNodeB, e.g. antenna and MIMO muting, may also be employed for energyefficient 5G base station.

Techniques used for energy efficiency for 2G/3G base stations forreducing feeder cable loss, using natural cooling and/or keeping heatdissipation from the base station module below the transmitter outputpower, and using alternative energy source may bring further improvementin energy efficiency. The base station may be transitioned into astandby/sleep mode during off-peak hours to reduce power consumption.Software-defined networks or software-defined radios may be employed toreduce the computational power requirements of the 5G base station alongwith the use of cloud computing at a coordinating server in a radioaccess network or in a core network

In general, for most cellular RF PA's (Macro, Micro), Doherty is usedfor efficiency, along with DPD to provide the linearization (removal ofspurious) at a reasonable cost ($). Other techniques exist withincreased efficiency, but at a greater cost unless consideration of muchhigher powers than are needed for cellular e.g. broadcast, it can bedifficult to justify the expense. As far as switching PA's on andoff—you need to consider thermal effects in the PA of rapidsurges/spikes are involved. Rapid switching is a problem resulting inthermal memory deep inside the PA device. However, in this case, I'dconsider it more in terms of coverage area. If you reduce the power(irrespective of time) you shrink the cell and remove coverage from thenetwork. If we can continue to “broadcast” in the cell and provide fullcell coverage, that would be better. Or if it were permitted tobroadcast less frequently. If the network knows that no active users arein a cell, near the cell, or likely to turn-on in the cell, then thismight work. Sort bursts of power will carry less data further, longburst of low power will carry more data, but over a shorter distance.PAs could be tuned in software to improve their efficiency in each case,but we would need more detail to work out the savings.

The PAs consume the majority of the power (at 8-12 W RF typical—assume3-4× energy input—they typically cover 500 Mhz wide (smaller channels ofthat 500 Mhz but they need to span it). If they can power it down evenfor milliseconds it can save a lot of energy. Managing the scheduler topack resource blocks into contiguous time with as much time between themhas a lot of value. If this is managed properly, then all we need is aperfect sync to the VSAT (perhaps the idea of sync-area-network whetherwireless or otherwise) and the VSAT can much more intelligently suchdown the PA. When trying to make rural work with VSATs this canmaterially reduce the size of the solar panels/backup batteries. Thisalso helps the CWS turn off the PA. This also plays into MIMO—if knowMIMO transmit is giving us very little for a given user—the schedulercan be managed further for those users on the second PA to be as closetogether as possible. It is further possible to run satellite basebandfrom extra 20 Mhz channels on a future Octasic powered CWS (themodulations seem comparable to a handset, 12 Mhz UL channels/20 Mhz DLchannels) of course you have to get the baseband to/from the VSATPA/receiver—in this configuration perhaps wigig is the way to go.

Also the satellite does have a source sync that is accurate to 1ppb—they use it to minimize guard bands for the MPTP transmissions. Oneway to not let any UE to access our eNB when our eNB is in hyper energyefficient mode is to increase the Qrxlev-min target that is broadcast bythe eNB. If this target is very high, the UE won't even get to camp onour eNB. That further reduces the UL processing requirements. Anotheridea is that with a 2-tx MIMO eNB, we can completely turn off the secondPA and then enable only the basic DL and UL control channels (asdescribed earlier). This will further improve the energy efficiency.With N tx antennas, you shut off N−1 PAs and the energy efficiency willbe more than 96% when N=32 antenna ports. You can also decide when toturn on/off the system based on the analytics engine running in the backend (on the Core or in the Gateway). The goal is to make the eNB energyefficient. This means not only the PAs for downlink transmission, butalso the uplink receiver blocks. Say, we have very few users in thesystem, and would like to offload the LTE users to some other accessmechanism. In rural areas, we might have zero users in the night (after10 PM) and before 6 AM.

Downlink: need to transmit reference signals on selected tones overselected OFDM symbols, need to transmit PDCCH on up to the first 3 OFDMsymbols, need to transmit PSS and SSS on the central 6 PRBs, and need totransmit PBCH. The above channels are bare minimum we must transmit. Allthe transmit antennas are active (as we need to send antenna-specificreference signals), but we are sending very few tones we cansignificantly scale back the per-antenna transmit power. If we have a PAto do this, then we can only send 1/10 or 1/20 of the max power duringthe eNB idle mode operation.

Uplink: Ideally, the entire UL chain can be shut off. However, it makessense to only keep the control and RACH processing on, and everythingelse off. That means, if you have a 20 MHz LTE system with 100 PRBs, andif you allocate 8 PRBs (max) for PUCCH and 6 PRBs for PRACH, yourbaseband is active only over 14/100=14% of the allocated PRBs. Further,since control channels and RACH can be configured in a sparse manner inthe frequency-domain (by the eNB), you can increase the overall energyefficiency significantly.

FIG. 14 is a diagram of a network 1400, in accordance with someembodiments. In the diagram, UEs 1401 are attached to eNodeB 1404, UEs1402 are attached to eNodeB 1405, and UEs 1403 are attached to eNodeB1406. eNodeBs 1404, 1405, 1406 are in communication using a gateway node1407, which itself is an eNodeB as well. Gateway node 1407 has twobackhaul connections (LTE and wired) to a gateway 1408, which is acoordinating node as described herein. Gateway node 1407 also has asecure IPsec tunnel with gateway 111. Gateway node 4107 also has aconnection with edge node 1408. The gateway 1408 is connected to a corenetwork 1410, and to an element management system (EMS) 1409 formanaging the nodes in the network.

FIG. 15 is an enhanced eNodeB 1500 for performing the methods describedherein, in accordance with some embodiments. Mesh network node 1500 mayinclude processor 1502, processor memory 1504 in communication with theprocessor, baseband processor 1506, and baseband processor memory 1508in communication with the baseband processor. Mesh network node 1500 mayalso include first radio transceiver 1512 and second radio transceiver1514, internal universal serial bus (USB) port 1516, and subscriberinformation module card (SIM card) 1518 coupled to USB port 1516. Insome embodiments, the second radio transceiver 1514 itself may becoupled to USB port 1516, and communications from the baseband processormay be passed through USB port 1516. The second radio transceiver may beused for wirelessly backhauling eNodeB 1500.

Processor 1502 and baseband processor 1506 are in communication with oneanother. Processor 1502 may perform routing functions, and may determineif/when a switch in network configuration is needed. Baseband processor1506 may generate and receive radio signals for both radio transceivers1512 and 1514, based on instructions from processor 1502. In someembodiments, processors 1502 and 1506 may be on the same physical logicboard. In other embodiments, they may be on separate logic boards.

Processor 1502 may identify the appropriate network configuration, andmay perform routing of packets from one network interface to anotheraccordingly. Processor 1502 may use memory 1504, in particular to storea routing table to be used for routing packets. Baseband processor 1506may perform operations to generate the radio frequency signals fortransmission or retransmission by both transceivers 1510 and 1512.Baseband processor 1506 may also perform operations to decode signalsreceived by transceivers 1512 and 1514. Baseband processor 1506 may usememory 1508 to perform these tasks.

The first radio transceiver 1512 may be a radio transceiver capable ofproviding LTE eNodeB functionality, and may be capable of higher powerand multi-channel OFDMA. The second radio transceiver 1514 may be aradio transceiver capable of providing LTE UE functionality. Bothtransceivers 1512 and 1514 may be capable of receiving and transmittingon one or more LTE bands. In some embodiments, either or both oftransceivers 1512 and 1514 may be capable of providing both LTE eNodeBand LTE UE functionality. Transceiver 1512 may be coupled to processor1502 via a Peripheral Component Interconnect-Express (PCI-E) bus, and/orvia a daughtercard. As transceiver 1514 is for providing LTE UEfunctionality, in effect emulating a user equipment, it may be connectedvia the same or different PCI-E bus, or by a USB bus, and may also becoupled to SIM card 1518. First transceiver 1512 may be coupled to firstradio frequency (RF) chain (filter, amplifier, antenna) 1522, and secondtransceiver 1514 may be coupled to second RF chain (filter, amplifier,antenna) 1524.

SIM card 1518 may provide information required for authenticating thesimulated UE to the evolved packet core (EPC). When no access to anoperator EPC is available, a local EPC may be used, or another local EPCon the network may be used. This information may be stored within theSIM card, and may include one or more of an international mobileequipment identity (IMEI), international mobile subscriber identity(IMSI), or other parameter needed to identify a UE. Special parametersmay also be stored in the SIM card or provided by the processor duringprocessing to identify to a target eNodeB that device 1500 is not anordinary UE but instead is a special UE for providing backhaul to device1500.

Wired backhaul or wireless backhaul may be used. Wired backhaul may bean Ethernet-based backhaul (including Gigabit Ethernet), or afiber-optic backhaul connection, or a cable-based backhaul connection,in some embodiments. Additionally, wireless backhaul may be provided inaddition to wireless transceivers 1512 and 1514, which may be Wi-Fi802.11a/b/g/n/ac/ad/ah, Bluetooth, ZigBee, microwave (includingline-of-sight microwave), or another wireless backhaul connection. Anyof the wired and wireless connections described herein may be usedflexibly for either access (providing a network connection to UEs) orbackhaul (providing a mesh link or providing a link to a gateway or corenetwork), according to identified network conditions and needs, and maybe under the control of processor 1502 for reconfiguration.

A GPS module 1530 may also be included, and may be in communication witha GPS antenna 1532 for providing GPS coordinates, as described herein.When mounted in a vehicle, the GPS antenna may be located on theexterior of the vehicle pointing upward, for receiving signals fromoverhead without being blocked by the bulk of the vehicle or the skin ofthe vehicle. Automatic neighbor relations (ANR) module 1532 may also bepresent and may run on processor 1502 or on another processor, or may belocated within another device, according to the methods and proceduresdescribed herein.

Other elements and/or modules may also be included, such as a homeeNodeB, a local gateway (LGW), a self-organizing network (SON) module,or another module. Additional radio amplifiers, radio transceiversand/or wired network connections may also be included.

FIG. 16 is mesh network base station 1600 or performing the methodsdescribed herein, in accordance with some embodiments. Mesh network node1600 may include processor 1602, processor memory 1604 in communicationwith the processor, baseband processor 1606, and baseband processormemory 1608 in communication with the baseband processor. Mesh networknode 1600 may also include first radio transceiver 1612 and second radiotransceiver 1614, internal universal serial bus (USB) port 1616, andsubscriber information module card (SIM card) 1618 coupled to USB port1616. In some embodiments, the second radio transceiver 1614 itself maybe coupled to USB port 1616, and communications from the basebandprocessor may be passed through USB port 1616. The second radiotransceiver may be used for wirelessly backhauling eNodeB 1600.

Processor 1602 and baseband processor 1606 are in communication with oneanother. Processor 1602 may perform routing functions, and may determineif/when a switch in network configuration is needed. Baseband processor1606 may generate and receive radio signals for both radio transceivers1612 and 1614, based on instructions from processor 1602. In someembodiments, processors 1602 and 1606 may be on the same physical logicboard. In other embodiments, they may be on separate logic boards.

Processor 1602 may identify the appropriate network configuration, andmay perform routing of packets from one network interface to anotheraccordingly. Processor 1602 may use memory 1604, in particular to storea routing table to be used for routing packets. Baseband processor 1606may perform operations to generate the radio frequency signals fortransmission or retransmission by both transceivers 1610 and 1612.Baseband processor 1606 may also perform operations to decode signalsreceived by transceivers 1612 and 1614. Baseband processor 1606 may usememory 1608 to perform these tasks.

The first radio transceiver 1612 may be a radio transceiver capable ofproviding LTE eNodeB functionality, and may be capable of higher powerand multi-channel OFDMA. The second radio transceiver 1614 may be aradio transceiver capable of providing LTE UE functionality. Bothtransceivers 1612 and 1614 may be capable of receiving and transmittingon one or more LTE bands. In some embodiments, either or both oftransceivers 1612 and 1614 may be capable of providing both LTE eNodeBand LTE UE functionality. Transceiver 1612 may be coupled to processor1602 via a Peripheral Component Interconnect-Express (PCI-E) bus, and/orvia a daughtercard. As transceiver 1614 is for providing LTE UEfunctionality, in effect emulating a user equipment, it may be connectedvia the same or different PCI-E bus, or by a USB bus, and may also becoupled to SIM card 1618.

SIM card 1618 may provide information required for authenticating thesimulated UE to the evolved packet core (EPC). When no access to anoperator EPC is available, a local EPC may be used, or another local EPCon the network may be used. This information may be stored within theSIM card, and may include one or more of an international mobileequipment identity (IMEI), international mobile subscriber identity(IMSI), or other parameter needed to identify a UE. Special parametersmay also be stored in the SIM card or provided by the processor duringprocessing to identify to a target eNodeB that device 1600 is not anordinary UE but instead is a special UE for providing backhaul to device1600.

Wired backhaul or wireless backhaul may be used. Wired backhaul may bean Ethernet-based backhaul (including Gigabit Ethernet), or afiber-optic backhaul connection, or a cable-based backhaul connection,in some embodiments. Additionally, wireless backhaul may be provided inaddition to wireless transceivers 1612 and 1614, which may be Wi-Fi802.11a/b/g/n/ac/ad/ah, Bluetooth, ZigBee, microwave (includingline-of-sight microwave), or another wireless backhaul connection. Anyof the wired and wireless connections described herein may be usedflexibly for either access (providing a network connection to UEs) orbackhaul (providing a mesh link or providing a link to a gateway or corenetwork), according to identified network conditions and needs, and maybe under the control of processor 1602 for reconfiguration.

Also shown is virtualization layer 1630 in communication with processor1602 and also in communication with local EPC 1620. Local EPC 1620includes HSS 1623, MME 1624, SGW 1626 and PGW 1628.

In some embodiments, the base stations described herein may supportWi-Fi air interfaces, which may include one or more of IEEE802.11a/b/g/n/ac/af/p/h. In some embodiments, the base stationsdescribed herein may support IEEE 802.16 (WiMAX), to LTE transmissionsin unlicensed frequency bands (e.g., LTE-U, Licensed Access or LA-LTE),to LTE transmissions using dynamic spectrum access (DSA), to radiotransceivers for ZigBee, Bluetooth, or other radio frequency protocols,or other air interfaces.

In any of the scenarios described herein, where processing may beperformed at the cell, the processing may also be performed incoordination with a cloud coordination server. A mesh node may be aneNodeB. An eNodeB may be in communication with the cloud coordinationserver via an X2 protocol connection, or another connection. The eNodeBmay perform inter-cell coordination via the cloud communication server,when other cells are in communication with the cloud coordinationserver. The eNodeB may communicate with the cloud coordination server todetermine whether the UE has the ability to support a handover to Wi-Fi,e.g., in a heterogeneous network.

Although the methods above are described as separate embodiments, one ofskill in the art would understand that it would be possible anddesirable to combine several of the above methods into a singleembodiment, or to combine disparate methods into a single embodiment.For example, all of the above methods could be combined. In thescenarios where multiple embodiments are described, the methods could becombined in sequential order, or in various orders as necessary.

Although the above systems and methods for providing interferencemitigation are described in reference to the Long Term Evolution (LTE)standard, one of skill in the art would understand that these systemsand methods could be adapted for use with other wireless standards orversions thereof. For example, 802.11n or 5G NR could be supported, aswell as any other OFDM radio standard.

The word “cell” is used herein to denote either the coverage area of anybase station, or the base station itself, as appropriate and as would beunderstood by one having skill in the art. For purposes of the presentdisclosure, while actual PCIs and ECGIs have values that reflect thepublic land mobile networks (PLMNs) that the base stations are part of,the values are illustrative and do not reflect any PLMNs nor the actualstructure of PCI and ECGI values.

In some embodiments, the software needed for implementing the methodsand procedures described herein may be implemented in a high levelprocedural or an object-oriented language such as C, C++, C#, Python,Java, or Perl. The software may also be implemented in assembly languageif desired. Packet processing implemented in a network device caninclude any processing determined by the context. For example, packetprocessing may involve high-level data link control (HDLC) framing,header compression, and/or encryption. In some embodiments, softwarethat, when executed, causes a device to perform the methods describedherein may be stored on a computer-readable medium such as read-onlymemory (ROM), programmable-read-only memory (PROM), electricallyerasable programmable-read-only memory (EEPROM), flash memory, or amagnetic disk that is readable by a general or specialpurpose-processing unit to perform the processes described in thisdocument. The processors can include any microprocessor (single ormultiple core), system on chip (SoC), microcontroller, digital signalprocessor (DSP), graphics processing unit (GPU), or any other integratedcircuit capable of processing instructions such as an x86microprocessor.

In some embodiments, the radio transceivers described herein may be basestations compatible with a Long Term Evolution (LTE) radio transmissionprotocol or air interface. The LTE-compatible base stations may beeNodeBs. In addition to supporting the LTE protocol, the base stationsmay also support other air interfaces, such as UMTS/HSPA, CDMA/CDMA2000,GSM/EDGE, GPRS, EVDO, other 3G/2G, legacy TDD, or other air interfacesused for mobile telephony.

In some embodiments, the base stations described herein may supportWi-Fi air interfaces, which may include one or more of IEEE802.11a/b/g/n/ac/af/p/h. In some embodiments, the base stationsdescribed herein may support IEEE 802.16 (WiMAX), to LTE transmissionsin unlicensed frequency bands (e.g., LTE-U, Licensed Access or LA-LTE),to LTE transmissions using dynamic spectrum access (DSA), to radiotransceivers for ZigBee, Bluetooth, or other radio frequency protocols,or other air interfaces.

The foregoing discussion discloses and describes merely exemplaryembodiments of the present invention. In some embodiments, softwarethat, when executed, causes a device to perform the methods describedherein may be stored on a computer-readable medium such as a computermemory storage device, a hard disk, a flash drive, an optical disc, orthe like. As will be understood by those skilled in the art, the presentinvention may be embodied in other specific forms without departing fromthe spirit or essential characteristics thereof. For example, wirelessnetwork topology can also apply to wired networks, optical networks, andthe like. The methods may apply to LTE-compatible networks, toUMTS-compatible networks, or to networks for additional protocols thatutilize radio frequency data transmission. Various components in thedevices described herein may be added, removed, split across differentdevices, combined onto a single device, or substituted with those havingthe same or similar functionality.

Although the present disclosure has been described and illustrated inthe foregoing example embodiments, it is understood that the presentdisclosure has been made only by way of example, and that numerouschanges in the details of implementation of the disclosure may be madewithout departing from the spirit and scope of the disclosure, which islimited only by the claims which follow. Various components in thedevices described herein may be added, removed, or substituted withthose having the same or similar functionality. Various steps asdescribed in the figures and specification may be added or removed fromthe processes described herein, and the steps described may be performedin an alternative order, consistent with the spirit of the invention.Features of one embodiment may be used in another embodiment. Otherembodiments are within the following claims.

1. A method for providing an energy efficient base station withsynchronization, comprising: performing traffic analysis to determineoff-peak hours duration when traffic is light; updating downlink anduplink schedulers to transmit a minimum required signaling and controlinformation; and wherein updating downlink and uplink scheduler forminimum required signaling and control information further comprisesscheduling, in a downlink direction, at least one of transmitting onlyreference symbols over selected OFDM symbols, PDDCH on to a first threeOFDM symbols, PSS and SSS on a central six PRBs and PBCH.
 2. The methodof claim 1, wherein updating downlink and uplink scheduler for minimumrequired signaling and control information further comprises scheduling,in an uplink direction, transmitting at least one of only PUCCH andPRACH.
 3. The method of claim 1, further comprising selecting theselected OFDM symbols based on measured past power efficiency.
 4. Themethod of claim 1, further comprising selecting the selected OFDMsymbols based on the selected OFDM symbols being contiguous with oneanother.
 5. The method of claim 1, further comprising selecting theselected OFDM symbols based on the selected OFDM symbols being at ornear a beginning or an end of a subframe.
 6. The method of claim 1,further comprising scheduling user data transmissions based on powerefficiency.
 7. The method of claim 1, further comprising identifyinguser equipments to handover to a macro base station or neighboring basestation.
 8. The method of claim 1, further comprising turning offadditional antennas, power amplifiers and Multiple In Multiple Out(MIMO) antennas.
 9. The method of claim 1, wherein performing trafficanalysis to determine off-peak hours duration when traffic is lightfurther comprises using self-organizing network (SON) for analysis ofuser activity and based on the analysis determining at least one of atime of day and a day of the week when a number of users are below apre-defined threshold.
 10. The method of claim 1, further comprisingincreasing energy efficiency by increasing a linearity of a poweramplifier.
 11. The method of claim 10, wherein increasing a linearity ofa power amplifier includes at least one of using feed forward,pre-distortion, Cartesian feedback, digital pre-distortion, Dohertypower amplifier and crest factor reduction.
 12. A non-transitorycomputer-readable medium containing instructions for providing an energyefficient base station with synchronization which, when executed, causea node to perform steps comprising: performing traffic analysis todetermine off-peak hours duration when traffic is light; updatingdownlink and uplink schedulers to transmit a minimum required signalingand control information; and wherein updating downlink and uplinkscheduler for minimum required signaling and control information furthercomprises scheduling, in a downlink direction, at least one oftransmitting only reference symbols over selected OFDM symbols, PDDCH onto a first three OFDM symbols, PSS and SSS on a central six PRBs andPBCH.
 13. The non-transitory computer-readable medium of claim 12further including instructions wherein updating downlink and uplinkscheduler for minimum required signaling and control information furthercomprises scheduling, in an uplink direction, transmitting at least oneof only PUCCH and PRACH.
 14. The non-transitory computer-readable mediumof claim 12 further including instructions for selecting the selectedOFDM symbols based on measured past power efficiency.
 15. Thenon-transitory computer-readable medium of claim 12 further includinginstructions for selecting the selected OFDM symbols based on theselected OFDM symbols being contiguous with one another.
 16. Thenon-transitory computer-readable medium of claim 12 further includinginstructions for selecting the selected OFDM symbols based on theselected OFDM symbols being at or near a beginning or an end of asubframe.
 17. The non-transitory computer-readable medium of claim 12further including instructions for scheduling user data transmissionsbased on power efficiency.
 18. The non-transitory computer-readablemedium of claim 12 further comprising instructions wherein performingtraffic analysis to determine off-peak hours duration when traffic islight further comprises using self-organizing network (SON) for analysisof user activity and based on the analysis determining at least one of atime of day and a day of the week when a number of users are below apre-defined threshold.
 19. A system for providing an energy efficientbase station with synchronization, comprising: a node configured toperform traffic analysis to determine off-peak hours duration whentraffic is light; update downlink and uplink schedulers to transmit aminimum required signaling and control information; and wherein thedownlink and uplink scheduler are updated for minimum required signalingand control information, including scheduling, in a downlink direction,at least one of transmitting only reference symbols over selected OFDMsymbols, PDDCH on to a first three OFDM symbols, PSS and SSS on acentral six PRBs and PBCH.
 20. The system of claim 19 wherein updatingdownlink and uplink scheduler for minimum required signaling and controlinformation further comprises scheduling, in an uplink direction,transmitting at least one of only PUCCH and PRACH.